To the problem of forming the high-strength concrete dispersed composition and properties

Abstract

Introduction. Significant disadvantages of currently used high-strength concrete are the high absolute consumption of binder as well as its low specific consumption per unit of strength. Including many components with the goal of multi-level optimization of the dispersed composition is one of the main methods for producing high-strength concretes with a minimum content of cement and high physical and mechanical properties. Obtaining such concretes can be connected with creating a dense high-aggregated solid phase of the constituents at various structural levels and low water-to-cement ratio. Materials and methods. he following components were used to study the properties and structure of the concrete: two fine aggregate fractions, granite-gabbro crushed stone of 5 to 10 mm fraction, portland cement of the CEM I 42.5N class, finely dispersed blast furnace granulated slag, metakaolin, silica fume, high-dispersed cement fraction, Glenium 430 superplasticizer, and high-valent hardening accelerator. The shape and size of the dispersed particles of the components were determined using a laser analyzer, the flowability of the concrete mixture was evaluated as per GOST 10181-2014 standard, while the concrete compressive strength following GOST 10180-2012 standard. The cement stone structure was studied using derivatographic analysis and x-ray phase analysis methods. Results. For concrete with an optimized dispersed composition, superplasticizer and high-valent hardening accelerator prepared using self-compacting concrete mixtures, the concrete strength at the age of 1 day after hardening was of 58,67 and 77 MPa and at the age of 28 days after hardening was of 150, 186 and 219 MPa under normal conditions and with cement consumption of 650, 710 and 770 kg/m3, respectively. Conclusions. Multi-level dispersion and granulometric modification in combination with chemical modification of the composition of self-compacting concrete mixtures is one of the most productive directions of research and synthesis of high-strength concrete with minimum consumption of Portland cement and high physical and mechanical properties. It is advisable to use several structural levels of the clinker component particles.